Access Cavity Preparation in Endodontics

Importance of Understanding Tooth Anatomy

• Knowledge of tooth anatomy helps in understanding morphology of the tooth, anatomy of the root canal system, number of canals, curvature and branching of the root canal system, length of the canal, position and size of the pulp chamber and its distance from the occlusal surface, and position of the apical foramen.
• It also helps in identifying calcification and resorption if present.

Objectives of Traditional Access Cavity Preparation

• Remove all caries when present
• Conserve sound tooth structure
• Unroof the pulp chamber completely
• Remove all coronal pulp tissue (vital or necrotic)
• Locate all root canal orifices and achieve straight-line access to the apical foramen or to the initial curvature of the canal

Key Steps in Traditional Access Preparation

Evaluating the Cementoenamel Junction

• The cementoenamel junction (CEJ) is the most important anatomic landmark for determining the location of pulp chambers and root canal orifices
• The pulp chamber of every tooth is in the center of the tooth at the level of the CEJ
• Physical identification of the shape and position of the CEJ can be accomplished by using a periodontal probe

Preparation of the Access Cavity

• Access cavities on anterior teeth are prepared through the lingual tooth surface
• Access cavities on posterior teeth are prepared through the occlusal surface
• These approaches are the best for achieving straight-line access while reducing esthetic and restorative concerns

Removal of Defective Restorations and Caries

• Removal of all defective restorations and caries is essential before entering the root canal system
• Hidden caries or fractures are often identified, and the ability to determine the restorability of the tooth is enhanced
• Leaving leaky restorations or caries can permit bacterial contamination during and following treatment

Preparation of Access Cavity Walls

• Sufficient tooth structure must be removed to allow instruments to be placed easily into each canal orifice without interference from canal walls
• Access design depends not only on the orifice location but also on the position and curvature of the entire canal

Instruments for Access Cavity Preparation

• Nos. 2 and 4 round diamond burs are used to gain entry into tooth structure and restorative materials

Definition and Importance of Access Cavity Preparation

• Access cavity preparation forms the foundation of endodontic treatment
• A proper coronal access cavity preparation enables unobstructed access to the canal orifices, a straight line access to apical foramen, and complete control over instrumentation
• A thorough knowledge of root canal anatomy and a study of preoperative periapical radiograph are essential before access cavity preparation